Furnace



Patented Mar. '15, 19 27.

' IUNITED ySTATES less expensive furnace is produced; also'to PATENT mics.

ROBERT K. Dawson, or A RON, NEW YORK.

FURNACE.

Application filed October 2, 1926, Serial No. 189,188, and in Canada January 304192 5.

7 This 1 invention relates to furnaces, and more particularly to hot air furnaces of the. type commonly used for heating buildings The objects of this invention are to con-v struct afurnace of this kind mainlyof sheet metal, so that a lighter, more eflicient. and

providea furnace of this kind with means for increasing the flow of air through the furnace; also to provide improved means for I arranging the feed and ash door openings on the furnace; also to provide improved means for supporting the fire pot inthe furnace; also to provide means of improved construction for increasing the radiation of heat from the combustion chamber into the' air space surrounding the same; also to provide improved means for mounting the grate on the furnace and also. to improve the construction'of furnaces of thiskind in the other respects hereinafterspecified. In the accompanyingdrawingsz I I,

Fig. 1 is an elevation, partly in section, of a furnace embodying the invention.

Fig. 2 is a sectionalplan view thereof, showing the top of the combustion chamber. Fig. 3 is a central, sectional elevation thereof on an enlarged scale on line 3 3, Fig. 2. v j I Fig. 4 is a fragmentary, sectional plan View thereof on line 4 l,-Fig.-3.

Fig. 5 is a fragmentary, perspective view of a part of, a shellof the combustion chamber showing portions of the shell bent outwardly to form the sides of the door opening.

Fig. 6 is a fragmentary, sectional elevation thereof on line 6 6, Fig. 2, showing the means for-increasing the radiating, capacity ofthe combustionfc'hamber. Fig. 7 is a front elevation of the heating, element detached from the furnace, the feed and ash doors being omitted. I r

Fig. 8 is afront elevation ofthelower part of the heater showing the feed and ash doors arranged thereon.

Fig.9 is a sectional, top plan viewof tlie furnace on line 9-9, Fig. 3.

Fig. 10 is a fragmentary, sectional plan view of the heater or heating element of the furnace on line 1010, Fig. 3.

. Fig. 11 is a fragmentary, sectional elevation thereof on an enlarged scale on line 11-11, Fig. 3. 1

Fig. 12 is a perspective view of a sectionof the refractory lining of the heater.

The furnace includes the usual heater or. vheatingelement comprising a combustion chamber A, a fire pot B, a grate C and an ash pit D, and the heater is surroundedzby a shell. E which is spaced from the wallsof the heater and is provided near-thelower pora tion thereof with a cold. air inlet'e. Frepresents the smoke pipe or duct of the heating element. Theupper portion of the outer shell or casing E is intended to .be provided with the usual pipes or ducts for conducting:

warm air to the rooms of abuilding, these Q pipes or ducts not being shown in? the drawings. It will be understood, however, that it is not intended to limit thislinve ntion toa furn e of this type since the inventiqn may be used inconnection 'Wlth furnacesof the 1 pipeless kind, in which case another shell would be provided, which would formwith the shell E a downward pas ge for thecold air. a The shell E may be of any suitable .or

desired construction.

Heretofore the heaters or heating elements of furnaces of this kindhave been coni v structed mainly of cast metal. In accordance with this invention, however the shell or housing of the heater is made of sheet metal which is bent into substantiallycylindricalform, a shell 15 being shown in the construction illustrated, which is formed 0f asingle sheet of metal, the edges of which aresuitably secured together, for example,

ably secured to the lower edge ofthe cylinbywelding as at 16. A-ri-ng 17 maybe suit The upper end .of the shell 15 of the heater is closed by means of a dome 2O whichiis 3 preferably also made of sheet metal, andithe edges of this dome preferably extend slight.

1y beyond the periphery of the shell 115 and are welded to ,the shell as shown at21 to insure a tight joint between the 'dome and 1 the shell. Other means for securing the dome to the shell may, however, 1 be used, if

desired. The dome preferably is also provided with a plurality of corrugations or annular bends 22 which may be of anysuitableshape and which serve the purposeof preventing buckling or deformation and possible separation of the same from the cylindrical wall during the expansion and contraction of the dome when subjected to different temperatures. 'These corrugations,

also increase the radiationof *heatfrom the dome. 1

The connection between thecombustion chamber A in the upper portion of the shell ends throughwhich air can pass.

walls of the channels 28 are preferably also constructed to admit air along the length of these channels or' flue's, a plurality of 15 and the flue F for the exhaust gases is effected by means of a down draft passage Gr, which is preferably formed of sheet metal and is spaced from the heater wall 15 'to'allow air to pass between the passage or radiator G and the heater. The passage or radiator G is" of considerable width and is curved or formed substantially concentric withthe heater wall 15. A short'pipe or flue 24- in the form of aflanged ring connects the passage or radiator G with a hole 25 in the cylindrical heater wall 15, and this pipe or flue 24' also serves to'sup'port'the passage or radiator G from the heater wall.

M Abafile 26 is preferably arranged in the lower' portion of the passage or radiator G'to' causethe products of combustion to passover the bottom wall of th'eradiator G to increase the amount of heat extracted from the radiator G. The lower portion of the passage or member G is provided with a hole or opening communicating with the flue or, smoke duct F. By providing a downflow passage',connect1ng'the flue or smoke duet with the top ofthe combustion 5- chamber instead of'connecting the flue directly to thetop of the combustion chamber, an increase in the efficiency of the'heater is obtained,since a considerableportion of the heat still remaining in'the gases and products of combustion passing through the opening 25 in the shell 15 is radiated through the relatively thin sheet metal wall 'of the downflow passage G and thus assists in heating the air in the airspacebetween theheater and the outer shell E of the furnace.

In'order to further assist in the transmisslon of the heat from the walls of th e com bustion chamber to the air surrounding the combustion chamber and to accelerate the upwardflow of the air surrounding the combustion chamber, a plurality of radiating finsfor channels may be arranged on the upper portion of'the shell 15 around the combustion chamber A. In the construction shown these fins or air flues 28 are substantially channel-shaped and the edges [thereof are suitably secured to the outer face of the shell 15, thus forming a plurality ofpassages open at'theirupper and lower holes 29 being provided for this purpose in the particular construction shown. These The outer v eaaeoc radiating fins 28 conduct the heat from the shell 15 and greatly increase the radiating surface of the shell and thus increase the efiiciencyyofthe heater, since the air pass- 111,9;01'1 both sides of the fins is heated, as

well as the air contacting with the outer face of the shell 15. I It has also been found that the columns of air in the channels or air flues 28, due to the heat imparted thereto both by the wall 15 and the channels or flues 28, and to the fact that the air is free to rise without encountering the frictional res stance to flow by other air 1n the air space around the heater, rise with a greatly accelerated speed, and thus increase the speed of fiow of all 'o f'the air through the air space by a stack effect causing a more pronounced upward movement of the air between the furnace casing and the shell by an injector'action of the air discharged by the fines, which 111.11111'1 increases'greatly "the efficiency of the furnace. The-flow of air upwardly in these channels or fins has been foundto be so rapid'that a considerable suction was formed within'the channels when imperforate or closed channels "were used, and consequently the flow of air in I the flues or fins 28 and through the entire air space in the furnace was further ac- "celerated by "providing air admission openings in the fins or flues, such, as the holes 29. It has been found that when the furnace is in operation, air enters all of these holes and thusnot only breaks the suction or partial vacuum in the channels or flues 28, but

also increases the volume of air passing upwardly in these air fines or fins, as well as the circulation of a r in'the entire heating system. However, a very considerable increase in efficiency can be obtained by the. use of channels or flues 28 without holes or openings therein, though still greater efficiency is obtainedwith the holes or openings. Other formsoffins, channels or flues may be used without departing from this invention.

preferably used in forming both the openings for the feed and the ash pit doors. Metal plates 33 are then cut or shaped to cooperate with the top and bottom edges of the side portions 82 of the-door openings and with the outer face of the shell 15 to form with the portions 82 outwardlyextendingopenings, and these plates are preferably welded at their edges.

all

I of cutting dies;

represents door frames suitably secured to the forwardly projecting portions ofthe heater, and ash and feed do0rs41 and 42 respectively" are mounted in the usual man'- ner on the door frame 40. By means ofthis arrangement, the sides of the doorfiopenings areintegral withthe' shell 15 of the heater and the top and bottom plates 33 are welded to the shell and sides .of the door openings so that theescape of gases or products of Combustion from the heater I into, the air space around the heater is prevented. Furthermore, this consfruction makes it possible i to use top and bottom plates for all door openings which are identical in size and form and can all be formed by the same set In order to prevent the heat of the fire from burning through or otherwise dai'nag ing the relatively thin, sheet metal plate of which the cylindrical wall of the heater is formed, the portion of-the cylindrical shell 15 surrounding the fire pot is preferably lined with or protected by a layer of fire brick, tile or other refractory substance.

.Means are, therefore, provided for suitably supporting the fire brick or refr actory lining within the shell 15, and these means are preferably also adapted to support the grates C. In the particular construction shown, the

refractory material 44 *is supported by a metal ledge or ring 45which is of angleshaped cross section and which is provided at intervals with lugs 46 adaptedtobe bolted or otherwise secured to the inner face of the shell 15. The upwardly extending flange of the angle-shaped portion of the support-- ing ledge. or ring 45 isv adapted toengagethe inner face of the lower portion ofthe refractory lining 44' and thusserves to hold this lining against displacement toward. the center of the heater while the shell '15 holds the,

lining against displacement in the opposite direction. The lining 44 in the construction shown is formed in a plurality of arc-shaped sections adapted to be fitted intothe'shell 15 ofthe furnace, and some'of the sections arranged adjacent to the feed door openingzare slightlylower than the other sections so as to permitrready access from the feed door I to the fire pot. Itisalso desirable that some circulation of air be'provided for between the passages 47.therein, nd this heated air urpose the several adds greatly to the efficiency of the combustion of the fuel.' In order to insure a thorough heating of the air before the same is discharged from the holes 48, theseveral sections ofthe lining at the rear and side of the furnacear-e provided at theirlower ends with outwardlyextending flanges 47 -and the supporting ring45 at these parts o'fthe 'furnaceextends; into close proximity tot-lie heater wall v15. At the front wall of the7 furnace the ring 45 is provided with recessed port-ions 45*, and the lower flange of the sections of refractory material is omitted, so that air can enter the spacevbetween the refractory material and the heater wall15 at 180 the front of thefurnace and circulate in the space 47, where. the air becomes'heated and from which space the heated air passes. through the openings 48.

The grateC maybe of any suitable con-" struction, but ispeferably in the. form of a single piece grid having a plurality of openingsorholes 49 therein through which air may pass upwardly to the fire and through which ashes may drop from the fire into the ash pit, and the central portion of the grate is preferably raised, as indicated at 50, to provide better distribution of air through the material in the fire pot to prevent the fire from burning too rapidly at the center of the fire pot. This grate, in the construction shown, is arranged within the ring 45 which supports the refractory lining,

and the grate is preferably provided at opposite sides with pivots or" trunnions 51,

preferably formed integral with the grate and adapted to rest on shelves or ledges-52 which are preferably formed'integral with the lining supporting ring 45, see particu larly Figs. and 11.

mit the furnace to be shaken by moving the grate substantially about itscenter through a small arc of a circle. Tofacihtate the shaking of 'the furnace, an integral projecd W tion or arm 54 extends downwardly andfor wardly from the grate C and is preferably suitably suspended on the furnace in such a manner as to permit-a certain amount of lateral movement of. the projecting arm when the furnace is being shaken. 'Any means for supportin'g'the arm 54 insu'c-h a manner as to enable the same to move later- {ally may be employed; In the construction shown, a ledge or bracket 55 s used which v is sec-uredon the lining supporting ring 45 and on which the'arm 54 rests so as to permit the arm tobe moved laterally to shake the ashes from the fire pot into the ash pit.

The shaking of the grate may be efiected in any desired manner, for example, by means of a lever 56 pivoted at 57 ona side of the furnace. A'reciprocatory bar-r58 is slidably arranged in the front;"portion of the furnace .andhas'atone enda-forked connection 59 These shelves or ledges 52' are preferably long enough to per- I sired.

- pit door.

with the grate arm 54:, and at the other end this bar is connected withthe lever to be actuated thereby. During the ordinary shakingofthe grate, the same receives a more or less rotary motion about its vertical of the supporting ledge 55, whereupon the grate is free to swing about the trunnions 51, so that the front end of the grate can swing downwardly to permit the contents of the fire pot to fall forwardly into the ash pit. The grate can readily be replaced into its normal position by placing the arm 54. between the forked connection 59 and then laterally upon the ledge 55. A grate of any other construction may be provided, if de- The furnace described has the advantage that the heater is made of a shell of comparatively thin metal so that the heat of the tire may readily pass through this shell and into the air in the space surrounding the shell. Furthermore, thecost of production of a furnace of this kind and the weight of the same is greatly reduced by using the comparatively light sheet metal shell 15 in place of the relatively heavy cast shells heretofore commonly employed. The lining or refractory material in the fire pot keeps the tire itself out of direct contact with the comparatively thin shell 15, and thereby avoids damage to this portion of the shell. A furnace of the construction described furthermore has the advantage that the sheet metal, such for example as sheet steel or iron, is practically free from the pores that are common in cast iron, and consequently witha furnace of the kind shown in the drawings, there is very little chance for gas or products of combustion to leak or pass from the heater into the hot air space surrounding the heater, sothat the smell of gas frequently experienced in housesheated by hot air furnaces iseliminated by means of this construction. Furthermore, the entire shell has only one longitudinal seam and another seam at the upper end thereof connecting the shell and dome, and when a welding process is used in connection with the making of these seams, they can easily be made absolutely gas tight. The construction described also makes it possibleto'readily apply the radiating fins described ltd the other face of. the shell of the heater, which feature adds greatly to the efficiency of the furnace; Because of the lightness of weight of the furnace, the same can be shipped and installed at a considerable saving of expense.

I claim as my'invention: i

1. In a furnace having an outer casing,

a heater arranged in said casing and including a tubular shell within which combustion takes place, and a plurality of channel strips secured with their open faces approximately against the outer face of said shell to extend upwardly along the same, each strip being casing surrounding said shell and all spaced apart from one another laterally around said shell, whereby the air confined in the channel of each of said strips by the wall of said shell will'be heated to a greater extent than the surrounding air in said casing and will have a stack effect causing a more pronounced upward movement of said surwithin said casing surrounding said shell and all spaced apart from one another laterally around said shell, whereby the air confined in the channel of each of said strips by' the wall of said shell will be heated to a greater extent than the surrounding air in said casing and will have a stack effectcaus 'ing a, more pronounced. upward movement of said surrounding air by the injector action of theair discharged by said fiu'es, the flues formed by the channels and shell being in communication with said surrounding air at points intermediate their ends.

3. In a furnace having an outer casing, a heater arranged in said casing and including. a tubular shell within which combustion takes place,'and a plurality of channel strips secured with their open faces approximately against the outer face of said shell to ex tend upwardly along the same, each strip being-open at both ends to the space within open at both ends to the space within said I said casing surrounding said shell and all spaced apart from one another laterally around said shell, whereby the air confined in the channel of each of said strips by the wall of said shell will be heated to a greater extent than the surrounding air in said casing and will have a stack effect'causing a more pronounced upward movement of said surrounding air by th injector action of the air discharged by said flues, said channel strips being apertured intermediate theirends to permit entrance to the rising air columns therein of some surrounding air.

4. A furnace having an outer casing, a heater in said casing and forming with said casing a space for the medium to be heated, a series of-upright open ended channels secured to said heater with their open sides v facing said heater and forming therewith passages for columns of the medium to be heated with openings at the sides of said columns for admission theretoof the medium to be heated. v

5. A furnace having an outer casing, a heater in said casing and forming with said casing a space for the medium to be'heated, a series of upright open ended channels securedto said heater with their open sides facing said heater and forming therewith passages for columns of the medium to be heated with openings at the sides of said columns for admission thereto of the medium to be heated, each of said channels having a plurality of apertures therein spaced apart along their length for the entrance to said passages of additional air.

6. A furnace having an outer casing, a

heater in said casing and forming with said casing a space for the medium to be heated,

a series of upright open endedchannels s cured at spaced apart intervals to said heater and extending into the space containing said medium to be heated'and forming passages for the columns of said medium, said columns having a seriesof openings in the sidesthereof for admission of the medium to be heated, said medium to be heated in said space receivingheat from portions of said 

